Vance’s mistake came earlier, immediately after the arrest, when he paraded his big catch before the media and wildly overstated the evidence against him. Prosecutors should be impartial arbiters of justice, and Vance acted like a cheap politician trying to score points.

DON EMMERT/AFP/Getty ImagesNew York District Attorney Cyrus Vance prepares to speak with reporters outside New York State Supreme court on July 1.

First, the criminal case. Strauss-Kahn may well be guilty of this crime. Prosecutors have semen samples. The encounter occurred minutes after the maid entered the room. And the defense claim that this was a consensual sexual encounter is implausible.

But the law requires proof, and Vance didn’t have it. In documents presented to the court
yesterday, prosecutors spelled out Nafissatou Diallo’s long history of making false statements.

It is not just that she lied to immigration officials about being gang-raped in Guinea. That kind of lie is reportedly common among those seeking asylum, and a single lie does not disqualify a woman from presenting credible testimony about a rape.

But Diallo changed her story about the events right after the alleged Strauss-Kahn encounter. And she discussed making money off the case with her fiancé in an Arizona jail, while she had told prosecutors the thought never entered her mind. Those lies are more to the point.

Vance knew the case was a loser, and he was right to ask the judge to drop these charges.

But flash back to the early days of this case, when police grabbed Strauss-Kahn from his plane, paraded him before the media in the disheveled state, and told reporters that the testimony from the alleged victim was solid. Vance was eager to cut the scalp from a powerful man, a sure way to win votes.

Yes, it is grating to watch him go free when there is a good possibility he is guilty of sexual assault. And it was annoying to hear him whine about what a “nightmare” this ordeal has been for him and his family.

But if it’s any comfort, his pathway to the French presidency is likely blocked now, he lost his job as head of the International Monetary Fund, and he still faces a rape charge in France. His nightmare is not over.